Galileo viewed all these circumstances in a different light. He resolved to compose a work in which the Copernican system should be demonstrated; but he had not the courage to do this in a direct and open manner. He adopted the plan of discussing the subject in a dialogue between three speakers, in the hope of eluding by this artifice the censure of the church. This work was completed in 1630, but, owing to some difficulties in obtaining a licence to print it, it was not published till 1632. In obtaining this licence, Galileo exhibited considerable address, and his memory has not escaped from the imputation of having acted unfairly, and of having involved his personal friends in the consequences of his imprudence. The situation of master of the palace was, fortunately for Galileo's designs, filled by Nicolo Riccardi, a friend and pupil of his own. This officer was a sort of censor of new publications, and when he was applied to on the subject of printing his work, Galileo soon found that attempts had previously been made to thwart his views. He instantly set off for Rome, and had an interview with his friend, who was in every respect anxious to oblige him. Riccardi examined the manuscript, pointed out some incautious expressions which he considered it necessary to erase, and returned it with his written approbation, on the understanding that the alterations he suggested would be made. Dreading to remain in Rome during the unhealthy season, which was fast approaching, Galileo returned to Florence, with the intention of completing the index and dedication, and of sending the MS. to Rome, to be printed under the care of prince Cesi. The death of that distinguished individual, in August 1630, frustrated Galileo's plan, and he applied for leave to have the book printed in Florence. Riccardi was at first desirous to examine the MS. again, but after inspecting only the beginning and the end of it, he gave Galileo leave to print it wherever he chose, providing it bore the licence of the inquisitor-general of Florence, and one or two other persons whom he named. Having overcome all these difficulties, Galileo's work was published in 1632, under the title of "The System of the World of Galileo Galilei, &c., in which, in four dialogues concerning the two principal systems of the World,--the Ptolemaic and the Copernican,--he discusses, indeterminately and firmly, the arguments proposed on both sides." It is dedicated to Ferdinand, grand duke of Tuscany, and is prefaced by an "Address to the prudent reader," which is itself characterised by the utmost imprudence. He refers to the decree of the inquisition in the most insulting and ironical language. He attributes it to passion and to ignorance, not by direct assertion, but by insinuations ascribed to others; and he announces his intention to defend the Copernican system, as a pure mathematical hypothesis, and not as an opinion, having an advantage over that of the stability of the earth absolutely.